But he played it coy when asked about the "Idol Gives Back" role of two other prominent people.

Bill and Melinda Gates, supporters of the fundraiser since it launched in 2007, "have done something very special, quite incredible, this year," Fuller said. Pressed for details, he would only advise that you must watch the broadcast.

Pumping up viewership — and donations — is Fuller's goal. "Idol Gives Back," which has raised more than $140 million, this year will benefit Children's Health Fund, Feeding America, Malaria No More, Save the Children's U.S. programs and the United Nations Foundation.

The fundraiser is airing as part of the weekly "American Idol" elimination episode (8-10 PM EDT, Fox), rather than a stand-alone broadcast. Seven contestants remain in the singing contest.

Others performing for "Idol Gives Back" are the Black Eyed Peas, Annie Lennox, Jeff Beck, Joss Stone and Mary J. Blige, with a pre-taped appearance by Justin Bieber. "American Idol" host Ryan Seacrest will be joined by Queen Latifah emceeing from a second theater.

"Everyone on this list is there for a good reason," Fuller said of the performers, citing their efforts on behalf of various causes. "They help us, and we can reflect some gratitude and recognition on their charity work."

Microsoft Corp. founder Gates and his wife co-chair the world's largest charitable foundation, which targets education, malaria vaccine development and other areas of need.

The recession will likely play a part in the event that's aired twice before, in better economic times.

Any amount people can give is appreciated but "we can't go into this with the same expectation," said Cecile Frot-Coutaz, CEO of series producer FremantleMedia North America and an "Idol" executive producer.

How the money is distributed is also affected. In the past, donations have been split between African and U.S. charities, she told a teleconference. "This year, (it's) a little bit more weighted toward domestic causes because we feel it is an American show," Frot-Coutaz said. "It's a very, very tough couple of years in this country and it's only fair that we focus on U.S. causes as well as some big international causes."